Research by IU geologists informs policy at Indiana Dunes National Lakeshore

An investigation that Indiana University geologists are conducting at the Indiana Dunes National Lakeshore provides a great example of science informing policy – in this case, the policy of making decisions about how to manage a popular public resource.

The researchers are mapping the internal structure of Mount Baldy, a 126-foot-tall dune near Michigan City, Ind. They are trying to understand why holes have been developing in the dune’s surface, including a giant hole that last summer buried a 6-year-old boy.

IU geologists, from left, Todd Thompson, Erin Argyilan and G. William Monaghan speak to news media at Mount Baldy.

IU geologists, from left, Todd Thompson, Erin Argyilan and G. William Monaghan speak to news media at Mount Baldy.

Principal investigators for the project are Erin Argyilan, an associate professor at IU Northwest; Todd Thompson, associate director for research with the Indiana Geological Survey at IU Bloomington; and G. William Monaghan, senior research scientist with the Indiana Geological Survey.

“The end result of this is we’re able to build a 3D model of the dune and essentially look inside of it and see where those collapses are occurring and what they are associated with,” Thompson said.

The researchers met last week with news media to explain their work. Standing before TV cameras on a ridge on Mount Baldy, they insisted on “letting the science do the talking” before drawing conclusions.

They began collecting data a year ago, and they are now completing an intensive, two-week project at the site. Focusing on an area near where the boy was buried, they are using grand-penetrating radar to create pictures of what lies under the surface. When the radar detects anomalies, they use a drilling machine to collect core samples of underground sand.

Last week, the researchers found another hole or “collapse feature” on the dune. Thompson stepped in a shallow depression and noticed the sand gave way. When he went back to inspect, there was a hole about 8 inches wide that opened to a depth of about 4½  feet.

Mount Baldy is a fast-migrating dune, pushed by the wind and moving 4 to 6 feet a year, covering mature trees and even old buildings as it goes. A leading theory of what’s happening is that buried trees and buildings decay, leaving a void that allows the sand to collapse.

The dune and the nearby beach and lake access area have been closed to visitors since last summer, and reporters pressed for information about whether, and when, they will reopen.

“We have a great desire to reopen it,” said Bruce Rowe, National Park Service spokesman for the national lakeshore. “It’s one of the most popular areas in the lakeshore. But we want to make sure we understand what’s going on from a geological standpoint so we can make the proper decisions.”

Another question is whether holes like those at Mount Baldy could be a problem at other dunes along the Lake Michigan shoreline. Maybe, the researchers said, but it doesn’t seem likely. Mount Baldy is relatively unique in that it’s migrating over a forested and formerly inhabited landscape.

Thompson, whose primary research focus has been past lake-level change in the Great Lakes, explained that the Indiana Dunes – some of the largest inland dunes in the world – were created about 4,000 years ago, in a period when the lake level fell rapidly.

Mount Baldy is unusual, he said, because Michigan City’s harbor has blocked its natural evolution, allowing winds to cause it to migrate away from the shore. Heavy foot traffic – the dune is a traditional spot for hiking and climbing – caused erosion and loss of vegetation, keeping the dune from stabilizing.

It’s an amazing story, and the best part is that 6-year-old Nathan Woessner of Sterling, Ill., not only survived but recovered after being trapped for three hours under 11 feet of sand on Mount Baldy.

“We worry when sand collapses,” Argyilan said. “There usually is not a lot of void space. So it really is a miracle that he survived and is doing well.”

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